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$Unique_ID{BRK03489}
$Pretitle{}
$Title{Arteriovenous Malformation}
$Subject{Arteriovenous Malformation AVM Spinal Arteriovenous Malformation
Arteriovenous Malformation of the Brain}
$Volume{}
$Log{}

Copyright (C) 1986, 1987, 1989, 1992 National Organization for Rare
Disorders, Inc.

221:
Arteriovenous Malformation

** IMPORTANT **
It is possible the main title of the article (Arteriovenous Malformation)
is not the name you expected.  Please check the SYNONYMS listing for find the
alternate names and disorder subdivisions covered by this article.

Synonyms

AVM

DISORDER SUBDIVISIONS

     Spinal Arteriovenous Malformation
     Arteriovenous Malformation of the Brain

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Arteriovenous Malformation is an inborn disorder affecting the central
nervous system that occurs in two main types:  in the spine or the brain
(cranial).  Blood vessels in these areas of the central nervous system are
enlarged and tortuous.  Arteries and veins may connect directly instead of
being connected by fine capillaries.  The malformation may be small and
localized or they may involve a large area; e.g., half the spinal cord.  They
may, like a mass lesion, compress or even replace normal tissue, or they may
rupture causing local or generalized bleeding.  The most common location in
the spinal cord is on the back of the cord at the level of the chest.  An
angioma visible on the skin may sometimes overlie the spinal AVM.

Symptoms

Spinal Arteriovenous Malformation is characterized by back pain associated
with sensory loss and leg weakness.  Acute hemorrhage occurs infrequently.
Urination is impaired early in the course of the disease.  Rarely, a murmur
at ausculation can be heard over the spine, or a blood vessel tumor (angioma)
on the skin may be observed.  For diagnostic purposes, an x-ray of the spine
is required which can show the distinctive worm-like impression of tangled
vessels.

There are three types of lesions noted in this disorder.  Type 1, the
most common, occurs in adults.  It is a single coiled vessel which generally
has a single feeding artery arising from another artery between the ribs or a
lumbar segmental artery.  This type of AVM is located dorsally and is often
surgically accessible.  Type 2 is less common and it also occurs in adults.
It is a glomus-type anomaly which is a localized knot of smaller coiled
vessels showing delayed opacification after injection of a contrast medium
prior to an x-ray.  This type of lesion also has a single feeding vessel.

Type 3 is strikingly different from types 1 and 2, and it most typically
occurs in children in the neck region.  This lesion has multiple feeding
vessels with a large malformation that often appears to fill the entire
spinal canal, and which demonstrates rapid flow with marked arteriovenous
shunting.  The multiple arterial feeders and location inside the spinal canal
nearly always preclude surgery and bleeding occurs more frequently.  Thus,
the overall prognosis of Type III is usually is usually the poorest.

Arteriovenous Malformations can also occur in the brain.  In 40% of
patients with AVM of the brain, the first symptom will be focal or
generalized seizures.  Headaches may occur with or without bleeding.  If an
AVM ruptures, bleeding will occur in the subarachnoid space under the inner
membrane of the brain or inside the brain itself.  Clinically, patients with
this type of AVM show symptoms similar to ruptured cerebral aneurysms
(dilation of an artery or vein).  A steal syndrome (the diversion of the
blood flow from its normal course) occurs as blood is shunted away from the
normal brain tissue toward the AVM which causes focal neurological deficits
secondary to ischemia (lack of oxygen in the blood).  The outcome depends on
the amount of bleeding to the area of the brain affected, size of the AVM,
and how the AVM responds to treatment.

A CAT scan (contrast-enhanced computerized tomographic scanning) of
spinal cord arteriovenous malformations may be useful in both screening and
follow-up procedures.  The development of the digital intravenous computerized
angiography (pictures of a blood vessel) may eventually replace common
angiography used at the present time.

Causes

The cause of Arteriovenous Malformation is not known.  AVM's are congenital
defects (the patient is born with the defect, it cannot be acquired).

Affected Population

Onset of symptoms from an Arteriovenous Malformation is from early childhood
to the ninth decade with a slight predominance in the male population.  The
outcome from bleeding in patients with Arteriovenous Malformation is better
than that for patients who have had an aneurysm.

A major study, followed for 35 years, showed the mortality rate at ten
percent.  Rebleeding in patients with AVM occurred in twenty percent of the
cases, with a one percent rate of fatal reoccurrence.

Therapies:  Standard

Treatment of Arteriovenous Malformation in the brain includes anticonvulsants
to control seizures.  Surgical removal can be attempted, and, if all the
arterial feeders can be identified and ligated, this procedure sometimes
cures the condition.  In most instances, however, the location and size of
these lesions precludes satisfactory therapy of AVM of the brain.

Spinal AVM surgery using specialized microtechniques is indicated if
spinal cord function is threatened.  Only neurosurgeons experienced in this
type of operation should attempt the procedure.

Therapies:  Investigational

For treatment of Spinal AVM, occlusion of feeder arteries by embolization
(which involves collapsing the veins by shooting plastic pellets into them
through a catheter) is being practiced on an experimental basis at a few
research institutions.

Patients with AVM of the brain have been treated experimentally with
stereotactic Bragg-peak proton-beam therapy.  This therapy is intended to
induce subendothelial deposits of a collagen and hyaline substance.  This
will hopefully narrow the lumens of small vessels and thicken the walls of
the malformation during the first 12 to 24 months following the performance
of the procedure.

The long-term benefits of the experimental therapies listed above are
unknown, and the risks of these procedures are not well understood.

Dr. Sadek K. Hilal, M.D., Ph.D., of the Health Sciences Department of
Columbia University, New York, NY, was awarded a grant in 1988 by the FDA
Orphan Products Division for his work in developing a treatment for
Arteriovenous of the Brain.  The treatment uses Percutaneous Embolization of
Viscoelastic Hylan Gel.

An important breakthrough in the treatment of AVM's and deep-seated brain
tumors is the use of the Gamma Knife, a Swedish-made machine.  The machine
uses gamma rays from 201 cobalt-60 radioactive sources to destroy swollen
brain arteries and both malignant and benign brain tumors.  This machine,
located at the University of Pittsburgh Medical Center, is the first and only
one of its type in North America.  The success rate for treatment of both
AVM's and brain tumors is very impressive.

This disease entry is based upon medical information available through
June 1992.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Arteriovenous Malformations, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     National Vascular Malformation Foundation
     8320 Nightingale St.
     Dearborn Heights, MI  48127
     [phone]

     NIH/National Institute of Neurological Disorders & Stroke (NINDS)
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]
     [phone]

References

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  Pp. 1389, 1432.

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W. B. Saunders Co., 1988.  P. 2060.